Rapier (oz6996)

 

Rapier (oz6996) by PE Norman 1962 - plan thumbnail

About this Plan

Rapier. Radio control IC ducted fan sport model. From June 1962 American Modeler.

Quote: "How to make a Ducted Fan Radio Control Flyer. PE Norman, outstanding scale and radio plane designer brings you his ducted fan 'Rapier.' PE's D/F has a great list of contest wins and exhibition flights to its credit.

This 34 in span swept wing ducted fan aircraft, although not an actual scale model is the culmination of a number of years development in ducted fan machines and is designed for the Cox Olympic, Fox 15 or K&B 15.

I have built two of these machines, both radio controlled and their performances are truly impressive. I have not flown them free flight, but with the elimination of the radio gear weight, I would guarantee the performance to be terrific with any of the above engines.

The models are immensely strong, and have on numerous occasions stuck into the grass or ground up to their intakes (when the rudder has jammed due to a wrong signal) without the slightest damage, much to the amazement of spectators and fellow modelers. The all-up weight with radio in each case when new is 38 oz. Therefore as free flight models it would be 32 to 34 oz.

My models are finished in two color schemes - grey blue upper surfaces, white undersurfaces - British red, white and blue roundels. These colors look very attractive in the air, besides serving the useful purpose of helping one to see which direction the machine is turning when under radio control.

Here are the building instructions for building one of these models. The sequence of operations appear in the order in which it is best to tackle construction:

1. Engine mount/wing tongue platform: Mark the shape accurately on a piece of resin-bonded 5-ply wood 1/4 in thick. Also the necessary cut away shapes on the center line to accommodate the particular engine to be used, and the fuel tank. With a scroll saw, cut out the platform and drill engine mounting bolt holes. Also drill hole for fuel line from tank.

Cut two small tin plates and drill for engine bolt holes. Screw bolts through these tin plates and up through ply platform. Lock bolts by soldering to tin plates. File and sandpaper to streamlined shape inner portions of platform between engine and inside of duct. Cut the two reinforcing pieces from medium balsa and carefully cut the slots in each to fit platform. Do not glue yet. Make streamline cone behind tank from either balsa or cork and drawing paper and thoroughly dope and fuel proof inside and out. Cut aluminum or dural saddle which passes under crankshaft case and fasten securely in position on ply platform with No.3-48 nuts and bolts.

Check engine and tank position and bolt engine temporarily in position. Cement streamline tailcone in position. Cut the hardboard disk; drill center to be snug fit in engine crankshaft, and file and sandpaper circumference to as true a circle as possible. This circle must be made accurately as its purpose is to ensure that the engine and mount are accurately placed in the duct.

Cut a 1 inch wide strip of 1/32 3-ply wood - grain running the length of the strip - and carefully wrap round circumference of hardboard disk, mark the overlap position accurately and glue (resin glue). Bind temporarily to hold till dry. (When dry, remove binding.)

Mount hardboard disk onto engine shaft and push plywood ring onto disk. Mark the positions where the ring touches the edge of ply platform, and make two saw cuts about 1/8 deep in platform, for the edge of the ring to fit into. Remove disk and ring from engine and build up oval section to ring with soft balsa wood glued to outer sides of ring with resin glue; hold in position with rubber bands till dry. Carve balsa wood away carefully till necessary shape is obtained, carving the inside parts each side of ply ring to a knife edge.

2. The Fan: This type of fan, which is the result of several years experiment, is extremely efficient and not too difficult to make, although accuracy is the key note. Make the blade pitch-cutting jig as shown in sketch. The hub of 9-ply wood may be turned on a lathe or, failing this, an octagon should be marked out carefully on the piece of 9-ply wood. The center drilled to take the crankshaft of the engine to be used.

Cut the octagon out with a hacksaw. Now with file and sandpaper smooth edges off the octagon until true circular shape is obtained. Fasten jig to hub, place both lightly in vise and carefully cut blade slots with hacksaw. Cut blades from 1/32 thick fibre to the length indicated.

File the edges off and sandpaper to streamlined section and curve section into blades by finger coaxing. Fasten blades into hub with resin glue, then drive a 3/8 shoe brad through the hub into each blade.

Mount fan onto the fan disk with suitable nut and bolt, and trim off each blade to about 1/32 under diameter of disk. Remove fan from disk and thoroughly dope and fuelproof. Replace disk and ring onto engine and platform. Make starter pulley from fuel can cap or as alternative method as shown in sketch..."

Update 26/1/2022: Replaced this plan with a clearer copy, thanks to Circlip. This fills in the missing band on sheet #1.

Direct submission to Outerzone.

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Rapier (oz6996) by PE Norman 1962 - model pic

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User comments

I got the magazine when I was going into high school. A FASCINATING article. Would be a great conversion to an electric ducted fan.
Phil Cartier - 24/01/2022
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Scaling

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